Although it can be applied to any desired aircraft or spacecraft, the present invention and the problems on which it is based are explained in more detail with reference to a passenger aircraft.
FIG. 9 shows a view of a cross section of a fuselage 1 of a conventional airliner. A floor 2 separates the fuselage in the vertical direction into a cabin 3 at the top, indicated by seats 4, and an underfloor space 5 at the bottom. The underfloor space 5 has a dividing wall 6, which is substantially airtight for fire protection reasons and divides the underfloor space 5 into an interior freight area 7 and a peripheral area 8 surrounding the said freight area and adjoining the fuselage shell 9.
During the operation of the aircraft, an air-conditioning system (not represented any further) produces a stream of air 12, which passes air from the cabin 3 into a drainage channel 13 provided in the lower region of the fuselage shell 9. In this region, referred to here as the fuselage floor, there is typically an aperture in the thermal insulation 14, which surrounds the fuselage shell 9 on its inner circumference. On account of the missing insulation, the region is much colder than the insulated regions of the fuselage shell 9 as a result of the cold atmosphere, in particular during the flight phase. This leads to condensation of water vapour in the stream of air 12. The condensate can consequently be carried away in a controlled manner by means of the drainage channel 13.
If, however, there is a fire 16 with a strong development of heat under the lower region of the fuselage shell 9 having the drainage channel 13, for example caused by a burning pool of kerosene on the runway, the missing insulation in the region of the drainage channel 13 proves to be very disadvantageous. The thin fuselage shell 9 burns through within a few seconds and there is the risk of a chimney effect, in which a stream of smoke and heat 17 penetrates into the cabin 3 in an extremely short time, potentially having serious consequences for the passengers.